Vaginal sponge contraceptives have gained favor as a single-use contraceptive providing a physical barrier to sperm entry to the cervical canal as well as a chemical barrier due to a chemical spermicidal agent typically included in the sponge. Vaginal sponges are formed of compressible polyurethane foam or other plastic foam material in the shape of a sphere, disc or doughnut. The sponge, when inserted into the vagina to cover the cervical area, has the ability to absorb sperm and block passage of sperm to the cervical canal. Additionally, spermicide may be released from the sponge to create the mentioned simultaneous chemical barrier. Disadvantages of the sponge include its expense and its large size and resultant bulky packaging requirements. Also, in its usual application, the sponge does not provide material protection against transmission of STDs.
The well-known diaphragm method of female vaginal contraception provides a physical barrier to passage of sperm to the cervical canal. The diaphragm is also used in association with spermicides. A major disadvantage of the diaphragm is the need for careful and accurate placement of the device so that it properly covers the cervix. In addition, because of the nature of diaphragms, they are unable to retain spermicidal agents except in the concave side of the "dome" diaphragm.
While the sponge and diaphragm, as well as other physical barrier female contraceptive devices such as the cervical cap, provide relatively reliable blockage of sperm to the cervical canal, and these devices may be used with spermicides, there is a need for a reliable, highly effective, low cost barrier contraceptive method that addresses the above mentioned disadvantages of the sponge and diaphragm while providing protection against both pregnancy and STDs.